Yuanning Li, Carnegie Mellon University, United States; Michael Ward, Mark Richardson, University of Pittsburgh, United States; Max G'Sell, Carnegie Mellon University, United States; Avniel Ghuman, University of Pittsburgh, United States

Abstract:

Perception of sensory inputs is modulated by shifts in endogenous ongoing brain activity. Specifically, previous studies have tied endogenous pre-stimulus neural activity to behavior in sensory tasks. However, it remains unclear whether the endogenous activity modulates neural coding and category tuning in visual processing, and if this modulation of tuning provides a neural pathway for behavioral modulation. To address these questions, we collected intracranial electroencephalography (iEEG) data from category-sensitive areas in ventral temporal cortex (VTC) in 32 patients. A statistical model was designed to decode the category of the stimulus and quantify the influence of pre-stimulus activity on post-stimulus category tuning in single trials. The results showed that conditioning on pre-stimulus activity improved the classification accuracy, indicating that category-selectivity was modulated by pre-stimulus activity in VTC. Furthermore, the aspect of the pre-stimulus activity that modulated category tuning correlated with reaction time in a 1-back task. The spatial and temporal specificity of this pre-stimulus modulation showed characteristics that distinguish it from global fluctuations in cognitive state or slow fluctuations in resting-state. Taken together, these results demonstrate that endogenous activity modulates category tuning. This modulation provides a potential neural basis for perceptual variation arising from shifts in endogenous ongoing activity.